The present invention relates to a series of novel 6-(4-substituted phenyl-3(2H)-pyridazinone derivatives and provides processes for their preparation, methods of using them and compositions containing them. The compounds of the invention are characterized by having a substituent on the 4-position of the phenyl group, which substituent is chosen from a limited class of substituted carbonylalkoxy or carbonylalkylthio groups.
The compounds of the invention have exhibited a variety of valuable therapeutic activities, including myocardial contractivity (notably a stimulant activity arising from potentiation of the contractions of the heart), anti-hypertensive activity, the ability to inhibit gastric secretions and the ability to inhibit platelet aggregation; however, it is envisaged that the primary value of the compounds of the invention will arise as a result of their myocardial contractivity.
A variety of 6-(substituted phenyl)-3(2H)-pyridazinones is known, and some of these are known to have useful cardiac activities. For example, certain such compounds are said in Japanese Patent Applications Kokai (i.e. as laid open to public inspection) No. 18884/72 and No. 8015/83 to have cardiac and anti-hypertensive activities. Other, similar, compounds are disclosed in British Patent Specification No. 1,383,906 (equivalent to U.S. Pat. No. 3,975,388 and U.S. Pat. No. 4,088,762) and these are said to have anti-hypertensive activity. British Patent Specification No. 1,488,330 discloses such compounds for use as .beta.-adrenergic blocking agents. Certain other such compounds are disclosed in J. Het. Chem., 11, 755 (1974), but only in the context of the discussion of synthetic procedures and no utility is disclosed for such compounds.
The prior art compounds referred to above differ from the compounds of the present invention in that the compounds of the invention all contain a substituted carbonylalkoxy or carbonylalkylthio substituent on the 4-position of the phenyl group and we have surprisingly found that certain compounds containing such a substituent possess significantly better myocardial contractivity than do the prior art compounds.